In the wake of the TWA Flight 800 accident, electric sensors situated in aircraft fuel tanks are being subjected to increasingly tighter restrictions. These mandates, among other factors, limit the amount of electrical energy that can enter a fuel tank to a level below that which could generate a spark and ignite an explosion, for example. These limitations apply to operating energy supplied to in-tank sensors under normal conditions as well as when the electrical equipment might fail, as well as when the aircraft is subjected to a lightning event.